University: Stiftung Fachhochschule Osnabrück (University of Applied Sciences)
Name of Sponsoring Professor: Prof. Dr.-Ing. Ralf Tönjes
Department: Faculty of Engineering and Computer Science

Um Simulationen auf Systemlevel durchzuführen, setzt das Labor für Hochfrequenztechnik und Mobilkommunikation das Softwareprodukt OPNET Modeler ein.
Dieses Werkzeug ermöglicht es, vordefinierte Simulationsmodelle zu konfigurieren und darüber hinaus neue Modelle auf Basis von Zustandsautomaten zu konzipieren. Jedem Zustand liegt eine Beschreibung in C-Code zugrunde. Das Labor nutzt die Erweiterungen „wireless“ und „UMTS“, um im Rahmen einen Praktikumsversuch bspw. die verschiedenen Handover-Arten (soft vs. hard) innerhalb einer UMTS-Infrastruktur zu vergleichen.

In order to carry out system level simulations, the Lab for RF-Technology and Mobile Communications uses the software OPNET Modeler.
This tool makes it possible to configure pre-defined simulations models and moreover to develop new models based on state machines. Every state can be programmed, using the programming language C. The Lab utilizes two extensions (“wireless” and “UMTS”) to enable the investigation of different types of handover techniques (hard vs. soft handover) within the UMTS architecture.

OPNET Modeler is used within the course Mobile Communication Systems (overview of class syllabus).

M. Knappmeyer, R. Tönjes, Adaptive Data Scheduling for Mobile Broadcast Carousel Services, 65th IEEE Vehicular Technology Conference, Dublin, Ireland, April 2007.

Several mobile operators have now started “broadcast-like” services, which are based on the channel delivery model, known from classical broadcast services likeradio and TV. Examples are goal notification for football fans (one club = one channel), news channels and mobile television in general. In order to efficiently support mobile broadcast services 3GPP has standardized Multimedia Broadcast Multicast Services (MBMS) for UMTS and GPRS in Release 6. The delivery of multicast/broadcast channels over capacity limited radio links requires intelligent scheduling mechanisms that make best use of the resources. The scheduler has to determine what content should be sent at which time in order to satisfy as many clients as possible. This work focuses on carousel based content delivery,
which means periodical retransmission of each content. The paper investigates the performance and computational complexity of different scheduling algorithms applied for mobile multicast. The algorithms then are enhanced to fulfill the identified requirements of MBMS which are mainly adaptation to new contents, adaptation to network congestion and adaptation to the clients’ demands. The simulation results are compared to conclude with recommendations for scheduling of mobile broadcast carousel services.

M. Knappmeyer, R. Chiang, N. Baker, R. Tönjes: Scheduling Techniques for Mobile Broadcast and Multicast Services, in "Advances in mobile and wireless communications – views of the 16th IST Mobile and Wireless Communication Summit", chapter 11, Springer, July 2008.

This chapter presents approaches and scheduling techniques for the provi-sion of broadcast and multicast services in 3G cellular networks. The de-scribed concepts are primarily designed for application in subscription based systems like MBMS (Multimedia Broadcast and Multicast Service). MBMS is an extension of UMTS (Universal Mobile Telecommunications System) specified by 3GPP (Third Generation Partnership Project) in its Release 6. Covering scheduling across different logical layers, this work proposes algorithms for reducing transmission power in the Radio Access Network as well as congestion control mechanisms. A Dynamic MBMS Resource Scheduler is introduced and the concept of Power Scheduling for multicast services is explained. The algorithms developed for deployment inside the Core Network comprise an efficient content scheduling solution for multicast streaming and an optimal broadcast circle for carousel ser-vices. A common feature of all presented algorithms is that they are able to maintain a defined Quality of Service. Proven by discrete event simulation, their performance enables cellular communication networks with means for efficient and affordable mass distribution of content. Scheduling will be one of the key components of service provisioning systems as the quan-tity of multicast and broadcast content starts to increase.

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